Amaladass E P, Devidas T R, Sharma Shilpam, Mani Awadhesh
Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, India.
J Phys Condens Matter. 2017 May 4;29(17):175602. doi: 10.1088/1361-648X/aa62e0. Epub 2017 Mar 24.
We report a comparative magnetotransport study on pristine and annealed BiSeTe single crystals. The pristine sample shows a metallic trend from 300 to 180 K, and an insulating behavior for T < 180 K, whereas the annealed sample exhibits an insulating nature in the entire 4.2-300 K temperature range. Magnetoresistance (MR) of pristine and annealed samples reveals contrasting behaviour as a function of temperature (T) and magnetic field (B). At 4.2 K, the pristine sample shows weak antilocalization (WAL) behavior at low fields and transforms to weak localization (WL) behavior (negative MR) for B > 2.5 T. Further, the quantum MR behaviours seen at low temperature gradually transform to classical B dependent upon increasing the temperatures. In contrast, the annealed sample shows a WAL at small field superimposed on a parabolic feature for B > ±4 T at low temperatures (T < 20 K). It shows a linear MR at intermediate temperatures (40 K < T < 100 K) and a parabolic MR at temperatures T > 100 K. Hall measurements on both samples exhibit a nonlinear behavior at 4.2 K pointing to the existence of two types of carriers with different mobility. The annealed sample also shows a drastic decrease in mobility by one order of magnitude and a reduction in Ioffe-Regel parameter (k l) by a factor of ~3. Disorder-induced localization of bulk carriers and its coexistence with localization-immune surface carriers at low T leads to WAL and WL. MR observed in the annealed sample can be attributed to the presence of both quantum-classical contribution and has been analysed using the Hikami-Larkin-Nagaoka (HLN) equation.
我们报告了对原始和退火的BiSeTe单晶的比较磁输运研究。原始样品在300至180 K呈现金属趋势，而在T < 180 K时表现出绝缘行为，而退火样品在整个4.2 - 300 K温度范围内都表现出绝缘性质。原始和退火样品的磁电阻（MR）显示出与温度（T）和磁场（B）相关的对比行为。在4.2 K时，原始样品在低场显示出弱反局域化（WAL）行为，而在B > 2.5 T时转变为弱局域化（WL）行为（负MR）。此外，低温下观察到的量子MR行为随着温度升高逐渐转变为经典的与B相关的行为。相比之下，退火样品在小场显示出WAL，在低温（T < 20 K）下B > ±4 T时叠加有抛物线特征。它在中间温度（40 K < T < 100 K）表现出线性MR，在温度T > 100 K时表现出抛物线MR。对两个样品的霍尔测量在4.2 K时都表现出非线性行为，表明存在两种具有不同迁移率的载流子。退火样品还显示迁移率急剧下降一个数量级，并且伊夫琴科 - 雷格尔参数（kl）降低约3倍。无序诱导的体载流子局域化及其在低温下与免疫局域化的表面载流子共存导致WAL和WL。在退火样品中观察到的MR可归因于量子 - 经典贡献的同时存在，并已使用日高 - 拉金 - 长冈（HLN）方程进行了分析。
